X-FLARE: The sun is no longer quiet. Emerging sunspot AR2339 unleashed an intense X2-class solar flare on May 5th at 22:11 UT. NASA’s Solar Dynamics Observatory captured the extreme ultraviolet flash:
A pulse of UV radiation and X-rays from the flare caused a strong radio blackout over the Pacific side of Earth. This map shows the extent of the blackout, which affected frequencies below 20 MHz. Mariners, aviators, and ham radio operators are the type of people who might have noticed the disturbance.
The explosion also hurled a CME into space: movie. Traveling faster than 1100 km/s (2.5 million mph), the expanding cloud does not appear to be heading for Earth.
In addition to causing a radio blackout, the flare also caused a radio burst. Immediately after the flare, a roar of static bellowed from the loudspeakers of shortwave receivers on Pacific isles and western parts of North America. Amateur radio astronomer Thomas Ashcraft of New Mexico recorded the outburst:
“The sound file is in stereo with one channel at 22 MHz and the other at 23 MHz,” says Ashcraft. “It is very intricate if listened to with headphones.”
What caused this burst of “solar static”? The same magnetic explosion that caused the flare also produced beams of electrons. As the electrons sliced through the sun’s atmosphere, they generated a ripple of radio-loud plasma waves. Astronomers classify solar radio bursts into five types; this one was a mixture of Type III and Type V.